The Swiss Ornithological Institute (SOI) has revealed that a record number of cranes have been spotted travelling across southern Germany and northern Switzerland this year. The findings bode well for birdwatchers, with the migratory period having only just begun.

Flock of 800 cranes spotted over Bavaria

The SOI has reported that a flock of around 800 cranes were spotted flying over Bavaria and Switzerland in recent weeks, a new record for the southern German state and alpine nation. Other large groups were also pictured flying over Swiss cities, remarkable considering that the crane's official migration season has only just begun.

Famous for their booming bird calls and air-force-esque flying V formations, cranes tend to migrate southwards during the autumn. They do this by using thermals in the air to gain altitude with minimal effort - the same phenomenon paragliders use to stay aloft. They then use this altitude to cross mountains and other major obstacles like the Mediterranean on their journey to Africa.

Why are cranes migrating over Bavaria and Switzerland more regularly?

Cranes don't typically favour the skies over Bavaria and Switzerland as migration routes, making their numbers this year all the more surprising. The birds tend to migrate southward to Africa either via Belarus, Ukraine, the Black Sea, Anatolia and the Levant, via the Hungarian steppe, the Balkans and the southern tip of Italy, or via the low countries, France, Spain and the straits of Gibraltar. These routes help avoid major obstacles like the Swiss Alps.

However, the SOI noted that since 2011, more and more cranes have started appearing in southern German and northern Swiss skies. Experts found that in that year, a favourable easterly wind meant that birds originally on the eastern European / Italian route changed course, travelling instead via southern Germany and Switzerland to France and on to Spain.

Cranes tend to internalise their migration routes via learned behaviour - word of beak if you will - meaning that the alternative route for heading south must be spreading rapidly among the population. Thanks to the change, “we too can increasingly enjoy the longing calls of migrating cranes,” the SOI concluded.

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